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JOSE, JWK and COSE

JWK parameters, key types and curves

JSON Web Key members, kty values and crv names of the IANA JOSE registry, including which members carry private key material and must never be published.

42 of 42 shown

JWK parameters · 29 entries

JSON Web Key members, which key types use them and which carry private key material.

NameDescriptionPrivate key materialReferences
algalg: Algorithm. Used with key types: *.NoRFC 7517, Section 4.4
crvcrv: Curve. Used with key types: EC, OKP.NoRFC 7518, Section 6.2.1.1RFC 8037, Section 2
dNoted: ECC Private Key. Used with key types: EC, RSA, OKP. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.2.2.1RFC 7518, Section 6.3.2.1RFC 8037, Section 2
dpdp: First Factor CRT Exponent. Used with key types: RSA. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.3.2.4
dqdq: Second Factor CRT Exponent. Used with key types: RSA. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.3.2.5
ee: Exponent. Used with key types: RSA.NoRFC 7518, Section 6.3.1.2
expexp: Expiration Time, as defined in [RFC 7519]. Used with key types: *.NoOpenID Federation 1.0, Section 8.7.2
extext: Extractable. Used with key types: *.NoW3C Web Cryptography API
iatiat: Issued At, as defined in [RFC 7519]. Used with key types: *.NoOpenID Federation 1.0, Section 8.7.2
kk: Key Value. Used with key types: oct. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.4.1
key_opskey_ops: Key Operations. Used with key types: *.NoRFC 7517, Section 4.3
kidNotekid: Key ID. Used with key types: *.NoRFC 7517, Section 4.5
ktykty: Key Type. Used with key types: *.NoRFC 7517, Section 4.1
nn: Modulus. Used with key types: RSA.NoRFC 7518, Section 6.3.1.1
nbfnbf: Not Before, as defined in [RFC 7519]. Used with key types: *.NoOpenID Federation 1.0, Section 8.7.2
othoth: Other Primes Info. Used with key types: RSA. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.3.2.7
pp: First Prime Factor. Used with key types: RSA. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.3.2.2
privpriv: Private key. Used with key types: AKP. It carries private key material and must never appear in a published JWK Set.YesRFC 9964
pubpub: Public key. Used with key types: AKP.NoRFC 9964
qq: Second Prime Factor. Used with key types: RSA. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.3.2.3
qiqi: First CRT Coefficient. Used with key types: RSA. It carries private key material and must never appear in a published JWK Set.YesRFC 7518, Section 6.3.2.6
revokedrevoked: Revoked Key Properties. Used with key types: *.NoOpenID Federation 1.0, Section 8.7.2
useuse: Public Key Use. Used with key types: *.NoRFC 7517, Section 4.2
xx: X Coordinate. Used with key types: EC, OKP.NoRFC 7518, Section 6.2.1.2RFC 8037, Section 2
x5cx5c: X.509 Certificate Chain. Used with key types: *.NoRFC 7517, Section 4.7
x5tx5t: X.509 Certificate SHA-1 Thumbprint. Used with key types: *.NoRFC 7517, Section 4.8
x5t#S256x5t#S256: X.509 Certificate SHA-256 Thumbprint. Used with key types: *.NoRFC 7517, Section 4.9
x5ux5u: X.509 URL. Used with key types: *.NoRFC 7517, Section 4.6
yy: Y Coordinate. Used with key types: EC.NoRFC 7518, Section 6.2.1.3

Source: JSON Object Signing and Encryption (JOSE) (IANA), retrieved 2026-10-20. Data license: CC0-1.0. JSON Web Key Parameters

Notes on notable entries

d

"d" is the private key: the ECC private scalar, the RSA private exponent or the OKP private key.

A JWK that contains 'd' is a private key and must never appear in a published JWK Set or be sent to a third-party service. ecdsa.com tools refuse JWKs with 'd'. The other RSA private members (p, q, dp, dq, qi, oth) and 'k' of symmetric keys are equally secret.

kid

"kid" names a key so a verifier can pick it out of a JWK Set; it carries no security meaning by itself.

The kid in a JWS header is matched against the kid of the keys in the issuer's JWKS (RFC 7517 §4.5). Values are application-defined; RFC 7638 thumbprints are a common choice. Rotating keys without changing kid leaves caches with a stale key and causes signature failures.

JWK key types · 5 entries

Registered values of the JWK kty member.

NameDescriptionRequirementReferences
AKPAlgorithm Key PairOptionalRFC 9964
ECElliptic CurveRecommended+RFC 7518, Section 6.2
octOctet sequenceRequiredRFC 7518, Section 6.4
OKPOctet string key pairsOptionalRFC 8037, Section 2
RSARSARequiredRFC 7518, Section 6.3

Source: JSON Object Signing and Encryption (JOSE) (IANA), retrieved 2026-10-20. Data license: CC0-1.0. JSON Web Key Types

JWK curves · 8 entries

Registered values of the JWK crv member.

NameDescriptionRequirementReferences
Ed25519Ed25519 signature algorithm key pairsedwards25519OptionalRFC 8037, Section 3.1
Ed448Ed448 signature algorithm key pairsedwards448OptionalRFC 8037, Section 3.1
P-256P-256 CurveP-256Recommended+RFC 7518, Section 6.2.1.1
P-384P-384 CurveP-384OptionalRFC 7518, Section 6.2.1.1
P-521P-521 CurveP-521OptionalRFC 7518, Section 6.2.1.1
secp256k1SECG secp256k1 curvesecp256k1OptionalRFC 8812, Section 3.1
X25519X25519 function key pairscurve25519OptionalRFC 8037, Section 3.2
X448X448 function key pairscurve448OptionalRFC 8037, Section 3.2

Source: JSON Object Signing and Encryption (JOSE) (IANA), retrieved 2026-10-20. Data license: CC0-1.0. JSON Web Key Elliptic Curve

All registries